Cylinder assembly for hermetic compressor

ABSTRACT

A cylinder assembly for a hermetic compressor includes a cylinder block having a cylinder in which a piston reciprocates; a cylinder head connected to a cylinder block to seal the cylinder, the head having an inlet hole and being divided by a partition into a first and a second discharge chamber that serve as an outlet path. A valve assembly formed between the cylinder block and the cylinder head, which controls refrigerant outlet and inlet to and from the cylinder according to different refrigerant pressures inside and outside the cylinder. When a sound wave (that is created as the suction valve or the discharge valve hits the valve plate) escapes to a discharge valve through a first and second discharge chambers, sound transmission loss occurs due to boundary interference and as a result, the sound wave is reduced. By this method, noise can be reduced in operating the compressor.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention is generally related to a compressor andmore specifically, to a cylinder assembly for a hermetic compressor.

[0003] 2. Description of the Prior Art

[0004] Generally, a cylinder assembly, as shown in FIGS. 1 and 3,includes a hermetic casing 100 wherein a drive unit 200 and acompression unit 300 are formed.

[0005] The hermetic casing 100 includes an upper casing 110 and a lowercasing 120, and an inlet tube 130 is formed in the hermetic casing 100.Lubricating oil is contained at the bottom of the lower casing 100.

[0006] The drive unit 200 includes a stator 210 fixed inside thehermetic casing 100, a rotor 220 which spins inside the stator 210, andalso a crank shaft 230 integrally formed with the rotor 220 to spinalong with the rotor 220.

[0007] The compression unit 300 consists of a connecting rod 310 that isconnected to an eccentric portion 240 of the crank shaft 230 and thatconverts circular movement of the rotor 220 into backward and forwardlinear movement of a piston 320, which is connected to one end of theconnecting rod 310. A cylinder assembly 400 accepts and guides thereciprocating motion of the piston 320.

[0008] The cylinder assembly 400 includes a cylinder block 420 having acylinder 410, a cylinder head 430 which is connected to the cylinderblock 420 to seal the cylinder 410, and a valve assembly 440 disposedtogether with gaskets 480, 490 between the cylinder block 420 and thecylinder head 430.

[0009] As shown in FIG. 1-3, the inside of the cylinder head 430 isdivided by a partition 431 into a suction chamber 432 and a dischargechamber 433. Formed at a side of the cylinder head 430 is an inlet hole434 (FIG. 2) to connect a suction muffler 500 and a suction chamber 432.

[0010] The cylinder block 420 has a discharge muffler 421 to reducenoise generated by compressed refrigerant flow. The discharge muffler421 is connected to the discharge chamber 433 of the cylinder head 430through an outlet path 422 which is formed in one side of the cylinderblock 420.

[0011] The valve assembly 440 includes a valve plate 450, a suctionvalve 460 and a discharge valve 470.

[0012] The valve plate 450 has a suction port 451 and a discharge port452. The cylinder 410 of the cylinder block 420 and the suction chamber432 of the cylinder head 430 are in fluid communication via the suctionport 451. Moreover, so are the cylinder 410 of the cylinder block 420and the discharge chamber 433 of the cylinder head 430 via the dischargeport 452.

[0013] The suction valve 460 is positioned near the cylinder block 420of the valve plate 450 in order to selectively open the suction port451. The suction valve 460 is formed by cutting out a part of thesuction valve sheet 461 disposed between the cylinder block 420 and thevalve plate 450. The discharge valve 470 is located nearby the cylinderhead 430 of the valve plate 450 in order to selectively open thedischarge port 452. Formed at the back of the discharge valve 470 byturns are a stopper 471 and a keeper 472 to control lift of thedischarge valve 470. The suction valve 460 and the discharge valve 470move freely according to pressure in the cylinder 410, opening andclosing the suction port 451 and the discharge port 452, which makes itpossible for refrigerant of the suction chamber 432 to flow into thecylinder 410 and for refrigerant of the cylinder 410 to be dischargedinto the discharge chamber 433. Specific explanation of prior cylinderassembly 400 follows with reference to FIG. 3.

[0014] When the piston 320 moves from an upper end of its travel to along end of its travel, a negative pressure in the cylinder 410 makesthe suction valve 460 move freely as shown in one dotted line of FIG. 3to open the suction port 451, causing the refrigerant to be drawn intothe cylinder 410 through the suction port 451.

[0015] Then, the piston 320 compresses the refrigerant in the cylinder410 by moving from the lower end of its travel toward the upper end ofits travel, and accordingly, the pressure of the cylinder 410 increases.As a result, the suction valve 460 is moved to close the suction port451, as shown in solid line of FIG. 3, by the high pressure in thecylinder 410.

[0016] Then, the piston 320 moves further towards its upper end of frontdead end, and the pressure of the cylinder 410 more increases. When thepiston 320 gets to the upper dead end of travel, the pressure inside thecylinder 410 is at its maximum. At this time, the cylinder pressure hasthe discharge valve 470 move as shown in solid line in FIG. 3, therebyopening the discharge port 452. Therefore, the compressed refrigerant inthe cylinder 410 is discharged into the discharge chamber 433 of thecylinder head 430 through the discharge port 452.

[0017] Meanwhile, the piston 320 having reached the upper end of itstravel, moves towards the lower end of its travel. During this movement,the discharge valve 470 moves (owing to recovery force) as shown insolid line in FIG. 3, to close the discharge port 452 and the suctionvalve 460 opens the suction port 451 again as the negative pressure isgenerated in the cylinder 410.

[0018] However, when the discharge valve 470 of the prior art cylinderassembly 400 opens and closes the discharge port 452, the recovery forcefrom a neck portion 470 a of the discharge valve 470 and from a bendingportion 471 a of the stopper 471 cause the discharge valve 470 to beclosed by striking the valve plate 450. Energy generated as the valveplate 450 is hit produces a noise-causing sound wave that is a problemof the conventional compressor: noise is produced when the compressor isoperated.

[0019] Moreover, the conventional cylinder assembly 400 has anotherdrawback: high manufacturing cost due to the big size of the valve plate450 and the suction sheet 461, and the complex structure of the valveassembly 440.

SUMMARY OF THE INVENTION

[0020] The present invention overcomes these problems of the prior art.The main object of the invention is to provides a quieter hermeticcompressor. This is achieved by applying a sound transmission losstheory, so that the sound wave generated when a discharge valve strikesa valve plate is discharged through two separate discharge chambers in acylinder head to a discharge muffler.

[0021] Another object of the present invention is to provide acost-effective cylinder assembly for a hermetic compressor by employinga small and simple valve assembly.

[0022] The novel cylinder assembly for hermetic compressors capable ofachieving the above objects includes a cylinder block having a cylinderin which a piston reciprocates, the cylinder head being connected to thecylinder block to seal the cylinder. The head is equipped with an inlethole, and a first and second discharge chambers serve as an outlet path.The valve assembly is located between the cylinder block and thecylinder head, and that assembly controls refrigerant outflow and onflow to and from the cylinder according to the pressure differenceinside and outside the cylinder.

[0023] A partition has one or more connecting holes to connect the firstand second discharge chamber.

[0024] Preferably, the partition is cylindrical, the space inside isdefined as the first discharge chamber, and it has a valve assemblyseating surface for the valve assembly to be mounted thereon. An inletpath is positioned inside the partition, but it is not connected to thefirst discharge chamber. Outside the partition is defined as the seconddischarge chamber.

[0025] It is preferable that the valve assembly has a valve plate havinga suction port for putting the inlet hole and the cylinder in fluidcommunication. A discharge port for putting the cylinder and the firstdischarge chamber in fluid communication. A suction valve sheet has asuction valve for opening and closing the suction port; and a dischargevalve sheet has a discharge valve for opening and closing the dischargeport. A gasket is located between the discharge valve sheet and thevalve assembly seating surface so as to block the inlet hole and thefirst discharge chamber. The gasket has an cut-away portion positionedto secure and limit the lift travel of the discharge valve.

[0026] In addition, it is desirable that the first discharge chamber hasa stopper portion for controlling the lift of the discharge valve, whichis formed at the same or lower height as that of the valve assemblyseating surface.

[0027] Also preferably, a cylinder gasket is located between thecylinder head and the cylinder block in order to seal the cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The aforementioned objects and characteristics of the presentinvention will become more apparent from the accompanying description ofa preferred embodiment of the present invention, and from reference tothe accompanying drawings, in which:

[0029]FIG. 1 is a sectional view showing a conventional hermeticcompressor;

[0030]FIG. 2 is an exploded perspective view showing a conventionalcylinder assembly;

[0031]FIG. 3 is a sectional view showing the conventional cylinderassembly of FIG. 2 in use;

[0032]FIG. 4 is an exploded perspective view showing a cylinder assemblyfor a hermetic compressor provided in accordance with a preferredembodiment of the present invention;

[0033]FIG. 5 is a sectional view showing the cylinder assembly of thepresent invention of FIG. 4 as it may appear when it is being assembled;and

[0034]FIG. 6 and 7 are sectional views showing the cylinder assemblyaccording to a preferred embodiment of the present invention as it mayappear when in use.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0035] Hereinafter, the following detailed description will present acylinder assembly for a hermetic compressor according to a preferredembodiment of the invention with reference to the accompanying drawings.In describing the present invention, the like elements will be given thesame reference numerals.

[0036] As shown in FIG. 4, a cylinder assembly for hermetic compressor600 according to the present invention includes a cylinder block 610, acylinder head 620, and a valve assembly 630. The cylinder block 610 hasa cylinder 611 with a piston 320 (See FIG. 5) and a discharge muffler612 (See FIGS. 6 and 7) for reducing discharge pulse pressures ofrefrigerant discharged from the cylinder 611. Formed on one side of thecylinder block 610 is an outlet path 613 connecting the cylinder to thedischarge muffler 612.

[0037] The cylinder head 620 is combined with the cylinder block 610 toenclose the cylinder 611 and has a partition 621 formed therein. (Thepartition 621 can take forms other than being cylindrical). Inside, thecylinder head 620 is divided by the partition 621 into a first 622 and asecond 623 discharge chamber. Formed inside the partition 621 are aninlet path 624 through which the refrigerant flows in, and a valveassembly seating surface 625 on which the valve assembly 630 is seated.As the inlet path 624 is connected to an inlet pipe 510 that is joinedwith the suction muffler 500, the refrigerant of the suction muffler 500(See FIG. 5) is directed into the inlet path 624 through the inlet pipe510.

[0038] The first discharge chamber 622 and the second discharge chamber623 are interconnected by a connecting hole 621 a formed in thepartition 621 and the second discharge chamber 623 is connected to theoutlet path 613 of the cylinder block 610. The more than one connectinghole 621 a can be provided. The compressed refrigerant escaping from thecylinder 611 is discharged to the first discharge chamber 622, and thento the second discharge chamber 623 through the connecting hole 621 a.

[0039] In the first discharge chamber 622, a stopper portion 626 isformed with the same or lower height as the valve assembly seatingsurface 625. The stopper portion 626 controls the lift of the dischargevalve 636 of the valve assembly 630 whereby the discharge valve 636swiftly opens and closes a discharge port 633 b.

[0040] The valve assembly 630 is cylindrical so that the valve assemblyseating surface 625 precisely fits with the partition 621. The valveassembly 630 includes a gasket 631, a discharge valve 632, a valve plate633 and a suction valve sheet 634. Inserted in the discharge chamber 622are, in order, of the gasket 631, the discharge valve sheet 632, thevalve plate 633 and the suction valve sheet 634. The valve assembly 630is substantially the same as the partition 621 in height.

[0041] Formed in the gasket 631, the discharge valve sheet 632 and thevalve plate 633 are suction ports 631 a, 632 a, 633 a connected to theinlet path 624, and the discharge ports 633 b, 634 a are formed on boththe valve plate 633 and the suction valve sheet 634.

[0042] The gasket 631 secures a space for a lift of the discharge valve636 towards the first discharge chamber 622 by spacing the valveassembly seating surface 625 apart from the discharge valve sheet 632.In other words, the gasket 631 has a cut-away portion 631 b whichcreates a lifting gap as thick as the gasket 631 between the valveassembly seating surface 625 and the discharge valve sheet 632.Therefore, the discharge valve 636 can be lifted towards the firstdischarge chamber 622 through the cut-away portion 631 b.

[0043] The suction valve sheet 634 has the suction valve 635 formedtherein in the form of a partly cut portion for selectively opening thesuction port 633 a. The same form also applies to the discharge valve636 formed on the discharge valve sheet 632 in order to selectively openthe discharge port 633 b.

[0044] Inserted between the cylinder block 610 and the cylinder head 620is a cylinder gasket 640 which seals between the second dischargechamber 622 and the cylinder 611 to prevent any refrigerant flow betweenthe two. There is a path hole 640 a in one part of the cylinder gasket640 to connect the second discharge chamber 623 and the outlet path ofthe cylinder block 610.

[0045] When the valve assembly 630 is assembled in the partition 621, itexactly fits into the partition 621 protrudes. Further, when thecylinder block 610 compresses the valve assembly 630 towards thecylinder head 620, the protrusion of the valve assembly 630 is pushedinto the partition 621, thereby causing the valve assembly 630 and thecylinder gasket 640 to fit without void.

[0046] A preferred embodiment of the present invention will be describedin greater detail with reference to FIGS. 6 and 7.

[0047] When the piston 320 moves from the upper dead center end to thelower dead center, the suction valve 635 is moved towards the cylinder611 due to negative pressure as shown in FIG. 6. As a result, thesuction port 633 a of the valve plate 633 is opened and consequently,the refrigerant of the inlet pipe 510 is drawn into the cylinder 611through the suction port 633 a.

[0048] Then, the refrigerant in the cylinder 611 is compressed as thepiston 320 moves from the lower dead end of its travel to the upper deadend of its travel and accordingly, the pressure in the cylinder 611rises. Because of the pressure, the suction valve 635 is moved as shownin dotted line of FIG. 6 to close the suction port 633 a.

[0049] When the piston 320 reaches the upper dead end of its travel, thepressure in the cylinder 611 maximizes. Then, the discharge valve 636opens to the first discharge chamber 622 of the cylinder head 620through the cut-away portion 631 b of the gasket 631 as shown in FIG. 7,opening the discharge port 633 b. The lift of the discharge valve 636 iscontrolled when the discharge valve hits the stopper portion 626 of thedischarge chamber 622. The compressed refrigerant in the cylinder 611 isdischarged to the first discharge chamber 622 of the cylinder head 620through the discharge port 633 b.

[0050] After the refrigerant in the first discharge chamber 622 flowsinto the second discharge chamber 623, it flows to the discharge muffler612 in the outlet path 613 of the cylinder block 610 after passingthrough the pass hole 640 a of the cylinder gasket 640.

[0051] According to the embodiment of the present invention, therefrigerant from the cylinder 611 passes through the first and seconddischarge chambers 622, 623 in the cylinder head 620, and consequently,the discharge pulsation is reduced. In addition, when the sound wave,which is generated when the suction valve 635 or the discharge valve 636hits the valve plate 633, escapes to the discharge valve 612 through thefirst and second discharge chamber 622, 623, sound transmission lossoccurs due to boundary interference and as a result, the sound wave isreduced. By this method, noise during operation of the compressor can bereduced.

[0052] Moreover, the refrigerant discharged from the cylinder 611 flowsto the discharge muffler 612 through both the first and the seconddischarge chambers 622, 623, so discharge pulsation is lessened.

[0053] In addition, according to the preferred embodiment of the presentinvention, parts of the valve plate 633, the suction valve sheet 634,the discharge valve sheet 632 and the discharge assembly 630 are smallin size and simple in design in order to be easily fit into the insidepartition 621. Because of this, cylinder assembly manufacturing costincluding material and assembling cost can be reduced.

[0054] Although the preferred embodiment of the present invention hasbeen described, it will be understood by those skilled in the art thatthe present invention should not be limited to the described preferredembodiment. Various changes and modifications can be made within thesprit and scope of the present invention as defined by the appendedclaims.

What is claimed is:
 1. A cylinder assembly for a hermetic compressorcomprising: a cylinder block having a cylinder in which a pistonreciprocates; a cylinder head connected to the cylinder block to sealthe cylinder, the head defining an inlet hole and being divided by apartition into a first and a second discharge chamber that serve as anoutlet path; and a valve assembly formed between the cylinder block andthe cylinder head, the valve assembly controlling refrigerant outletflow and inlet flow to and from the cylinder.
 2. The cylinder assemblyas recited in claim 1, wherein the partition has at least one connectinghole to connect the first and second discharge chambers.
 3. The cylinderassembly as recited in claim 1, wherein the partition is cylindrical,the space inside being defined as the first discharge chamber the spaceoutside the second discharge chamber, the first discharge chamber havinga valve assembly seating surface for the valve assembly being mountedthereon, and the partition being provided with an inlet path thereinformed without connection to the first discharge chamber.
 4. Thecylinder assembly as recited in claim 3, wherein the valve assemblycomprises: a valve plate having a suction port for connecting the inlethole and the cylinder in fluid communication, and a discharge port forconnecting the cylinder and the first discharge chamber in fluidcommunication; a suction valve sheet having a suction valve for openingand closing the suction port; a discharge valve sheet having a dischargevalve for opening and closing the discharge port; and a gasket betweenthe discharge valve sheet and the valve assembly seating surface so asto block the inlet hole and the first discharge chamber, which has acut-away portion that is positioned to limit a lifting gap of thedischarge valve.
 5. The cylinder assembly as recited in claim 4, whereinthe first discharge chamber has a stopper portion for controlling liftof the discharge valve, which is formed at the same or lower height asthe valve assembly seating surface.
 6. The cylinder assembly as recitedin claim 1, wherein a cylinder gasket is located between the cylinderhead and the cylinder block to seal between the second discharge chamberand the cylinder.